Sieges and attacking AI = Worst AI in gaming history.

I find 95% of all sieges involving stone walls end in disaster for the AI. The last siege I set up had 2 AI armies attacking a stone wall city with my faction inside along with a few Senate units. The AI had 2-3 ladders each and a siege tower. None of the ladders were used - in fact half the ladders went in one direction, the others in the opposite direction, looking like something out of a Laurel & Hardy comic sketch. With one siege tower burnt, one tower is all they had to take on my city and were promptly killed. There seems to be some kind of basic error that makes the AI not use its siege equipment until a certain situation arises, as later on, perhaps when a section of wall has been stripped of its defenders , the attackers spring into action and try and use ladders and towers, but usually their army is all but dead by that stage. For whatever reason, they get stuck in a mode of being unable to do anything - except die, thus making you cringe painfully at their ineptitude.

Worst ever siege I had involved 3 AI reinforcement armies helping me assault a stone wall settlement. 11,000 men, around 8 sets of ladders, 3-4 siege towers, 3 rams, and only one of the siege towers was used and one ladder. At least 5,000 of the 7,000 men I lost were due to the AI controlled ones standing in front of towers and dying.

There is the occasional good siege battle, although most of them involve wooden pallisades, or better still, an unprotected Roman village. I recommend trying village battles, especially with 2-3 enemies - you'll be swamped from all sides.